Goodwin Conservation Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Goodwin Conservation Center clear sky chart from 2005-11-06 to 2024-01-13.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
25%
23007
19%
74561
8%
22964
38%
22964
19%
48445

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
15%
760
22%
2649
7%
757
34%
757
17%
1612
January11th to 20thNight
15%
729
17%
2549
4%
729
32%
729
12%
1736
January21st to endNight
16%
792
21%
2772
6%
792
36%
792
16%
1700
February1st to 10thNight
16%
720
17%
2242
5%
720
31%
720
15%
1512
February11th to 20thNight
10%
703
21%
2100
4%
700
30%
700
15%
1407
February21st to endNight
13%
592
23%
1776
7%
592
33%
592
14%
1193
March1st to 10thNight
16%
720
21%
2160
6%
720
35%
720
18%
1400
March11th to 20thNight
17%
720
19%
2094
5%
720
32%
720
18%
1416
March21st to endNight
17%
792
23%
2012
5%
792
30%
792
20%
1383
April1st to 10thNight
19%
720
19%
1800
4%
720
28%
720
19%
1274
April11th to 20thNight
21%
711
16%
1775
4%
711
28%
711
22%
1249
April21st to endNight
17%
574
19%
1654
5%
574
27%
574
19%
1134
May1st to 10thNight
21%
540
13%
1620
5%
540
28%
540
15%
1156
May11th to 20thNight
21%
488
17%
1550
8%
488
32%
488
17%
1036
May21st to endNight
33%
389
12%
1551
9%
388
41%
388
16%
1000
June1st to 10thNight
33%
360
14%
1440
11%
360
45%
360
17%
919
June11th to 20thNight
35%
360
13%
1440
13%
360
44%
360
18%
912
June21st to endNight
40%
360
13%
1440
12%
360
50%
360
21%
871
July1st to 10thNight
43%
350
13%
1400
15%
350
49%
350
19%
894
July11th to 20thNight
45%
348
12%
1392
13%
348
50%
348
19%
869
July21st to endNight
44%
394
17%
1486
16%
372
51%
372
22%
890
August1st to 10thNight
44%
466
16%
1530
11%
464
49%
464
26%
955
August11th to 20thNight
44%
627
17%
1691
10%
627
47%
627
25%
1156
August21st to endNight
47%
792
21%
1980
10%
792
51%
792
35%
1284
September1st to 10thNight
35%
720
19%
1800
7%
720
42%
720
27%
1241
September11th to 20thNight
42%
720
25%
1956
14%
720
50%
720
32%
1213
September21st to endNight
36%
720
23%
1980
14%
720
45%
720
25%
1339
October1st to 10thNight
33%
720
18%
1980
10%
720
40%
720
22%
1357
October11th to 20thNight
30%
720
22%
2194
9%
720
46%
720
25%
1379
October21st to endNight
22%
792
16%
2574
7%
792
35%
792
18%
1700
November1st to 10thNight
30%
740
23%
2407
10%
740
46%
740
24%
1446
November11th to 20thNight
21%
760
24%
2470
9%
760
40%
760
19%
1538
November21st to endNight
23%
760
23%
2470
8%
760
42%
760
20%
1512
December1st to 10thNight
20%
760
20%
2642
7%
760
35%
760
16%
1714
December11th to 20thNight
19%
760
18%
3200
5%
759
35%
759
13%
1997
December21st to endNight
15%
828
14%
4785
4%
817
34%
817
9%
3051

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
17%6%35%5%3445%7%40%
74797
Night
18%7%35%5%3445%6%41%
74919
TransparencyDay
44%6%11%22%15%2
74502
Night
44%5%11%22%15%2
74748
SeeingDay
25%16%31%19%7%2
13932
Night
23%15%31%23%7%1
23015

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
15%7%245%345%5%6%44%
1517
11th to 20thDay
19%7%35%5%35%5%6%7%35%
1456
21st to endDay
14%8%35%435%45%7%43%
1584
February1st to 10thDay
20%7%35%5%36%45%7%35%
1714
11th to 20thDay
15%6%25%6%35%5%5%7%41%
1748
21st to endDay
21%10%35%43435%5%36%
1480
March1st to 10thDay
17%8%35%424447%43%
1797
11th to 20thDay
17%7%35%5%35%5%6%6%37%
1864
21st to endDay
20%8%35%5%3434440%
2340
April1st to 10thDay
19%7%25%5%245%5%7%38%
2160
11th to 20thDay
18%6%2443445%7%43%
2134
21st to endDay
22%6%35%5%44446%37%
2304
May1st to 10thDay
26%6%35%5%3445%7%33%
2340
11th to 20thDay
20%6%3443445%7%41%
2359
21st to endDay
16%6%25%5%24448%42%
2725
June1st to 10thDay
19%6%26%6%45%5%6%8%34%
2520
11th to 20thDay
17%6%25%6%35%5%6%9%35%
2520
21st to endDay
16%6%26%5%346%7%9%36%
2520
July1st to 10thDay
14%6%347%45%5%6%8%39%
2520
11th to 20thDay
14%5%35%5%35%5%6%10%38%
2520
21st to endDay
13%5%36%5%46%5%6%8%38%
2744
August1st to 10thDay
12%7%25%7%45%6%6%9%36%
2378
11th to 20thDay
14%7%35%5%45%6%6%8%38%
2206
21st to endDay
12%5%36%6%4446%8%42%
2376
September1st to 10thDay
16%6%25%5%345%5%6%43%
2160
11th to 20thDay
15%42442345%6%50%
2003
21st to endDay
18%6%25%33445%7%43%
1980
October1st to 10thDay
24%7%25%323345%41%
1980
11th to 20thDay
16%6%34423446%48%
1762
21st to endDay
20%7%345%3335%6%40%
1782
November1st to 10thDay
14%7%25%424345%48%
1671
11th to 20thDay
19%6%2432445%6%46%
1710
21st to endDay
17%6%26%4345%47%44%
1710
December1st to 10thDay
20%6%345%345%6%6%37%
1535
11th to 20thDay
22%7%23423345%45%
1906
21st to endDay
20%11%36%5%24446%35%
2772
January1st to 10thNight
16%7%35%434447%44%
2649
11th to 20thNight
21%8%35%5%24447%36%
2549
21st to endNight
13%9%35%43445%6%43%
2772
February1st to 10thNight
18%8%46%5%34345%40%
2242
11th to 20thNight
17%7%35%5%345%5%7%39%
2098
21st to endNight
19%8%26%6%235%5%5%39%
1776
March1st to 10thNight
17%7%25%42446%7%41%
2150
11th to 20thNight
15%7%35%5%345%5%7%39%
2093
21st to endNight
19%8%244345%5%6%41%
2012
April1st to 10thNight
19%7%35%5%35%5%6%6%37%
1800
11th to 20thNight
19%6%35%6%3445%7%39%
1775
21st to endNight
23%7%26%42345%6%39%
1654
May1st to 10thNight
22%8%36%5%445%5%7%32%
1620
11th to 20thNight
19%6%35%5%3445%9%37%
1549
21st to endNight
18%6%25%5%3446%7%40%
1550
June1st to 10thNight
18%6%35%5%245%5%8%38%
1440
11th to 20thNight
19%6%35%5%25%45%8%38%
1440
21st to endNight
13%6%345%345%6%9%42%
1440
July1st to 10thNight
14%5%26%5%36%5%6%8%39%
1440
11th to 20thNight
16%6%35%5%35%6%7%9%35%
1440
21st to endNight
13%6%36%6%35%5%6%7%42%
1574
August1st to 10thNight
9%6%35%5%35%6%6%9%42%
1540
11th to 20thNight
11%6%36%7%45%6%6%8%39%
1691
21st to endNight
15%5%25%42345%7%48%
1980
September1st to 10thNight
15%6%36%5%35%5%5%6%42%
1800
11th to 20thNight
14%6%35%423346%52%
1956
21st to endNight
17%6%25%425%446%43%
1980
October1st to 10thNight
21%7%35%423436%41%
1980
11th to 20thNight
16%6%244345%5%6%46%
2194
21st to endNight
22%7%26%42345%5%39%
2574
November1st to 10thNight
14%6%25%423446%49%
2407
11th to 20thNight
19%7%24423445%45%
2470
21st to endNight
16%6%25%42435%7%45%
2470
December1st to 10thNight
21%7%26%424346%40%
2642
11th to 20thNight
21%6%24434446%41%
3288
21st to endNight
22%11%35%423335%38%
4884

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
40%5%9%29%13%3
1518
11th to 20thDay
47%6%14%20%12%2
1456
21st to endDay
40%5%12%25%16%3
1584
February1st to 10thDay
49%5%13%19%13%2
1714
11th to 20thDay
44%5%10%22%15%3
1757
21st to endDay
51%49%20%14%3
1480
March1st to 10thDay
43%413%22%15%4
1800
11th to 20thDay
45%410%23%13%3
1864
21st to endDay
48%48%17%17%6%
2340
April1st to 10thDay
46%5%10%20%15%4
2160
11th to 20thDay
41%5%10%21%19%3
2134
21st to endDay
48%5%9%20%15%3
2304
May1st to 10thDay
51%5%9%20%13%2
2340
11th to 20thDay
43%6%8%22%18%3
2363
21st to endDay
40%6%15%22%14%2
2725
June1st to 10thDay
47%6%12%23%11%1
2520
11th to 20thDay
45%7%12%21%13%1
2520
21st to endDay
43%9%12%21%14%1
2520
July1st to 10thDay
43%7%10%23%15%2
2450
11th to 20thDay
41%7%14%25%11%2
2445
21st to endDay
41%7%13%20%15%3
2591
August1st to 10thDay
42%8%14%22%13%1
2364
11th to 20thDay
42%7%14%23%14%1
2206
21st to endDay
39%8%9%23%19%2
2376
September1st to 10thDay
41%6%11%22%18%2
2160
11th to 20thDay
34%6%10%23%24%3
2003
21st to endDay
41%5%9%21%22%2
1980
October1st to 10thDay
47%5%8%21%16%4
1980
11th to 20thDay
38%412%27%17%1
1762
21st to endDay
45%411%21%15%3
1782
November1st to 10thDay
40%5%12%21%20%2
1671
11th to 20thDay
38%5%11%22%20%3
1710
21st to endDay
42%410%27%13%3
1710
December1st to 10thDay
47%5%13%17%16%1
1535
11th to 20thDay
43%414%18%18%3
1906
21st to endDay
51%5%11%22%10%1
2772
January1st to 10thNight
42%312%24%16%3
2649
11th to 20thNight
50%5%12%21%10%3
2549
21st to endNight
42%411%21%19%3
2772
February1st to 10thNight
47%5%12%22%12%2
2242
11th to 20thNight
45%5%10%20%15%4
2100
21st to endNight
47%48%22%15%3
1776
March1st to 10thNight
42%5%11%24%15%4
2160
11th to 20thNight
45%5%10%20%16%3
2094
21st to endNight
45%48%18%19%6%
2012
April1st to 10thNight
46%6%10%21%14%3
1800
11th to 20thNight
45%5%9%20%18%2
1775
21st to endNight
47%5%10%21%13%5%
1654
May1st to 10thNight
51%6%11%17%13%3
1620
11th to 20thNight
46%6%11%19%15%3
1550
21st to endNight
43%9%17%18%12%1
1551
June1st to 10thNight
45%7%13%20%14%1
1440
11th to 20thNight
44%7%14%23%11%1
1440
21st to endNight
38%9%15%25%13%
1440
July1st to 10thNight
42%9%12%21%14%1
1400
11th to 20thNight
42%8%15%26%8%1
1392
21st to endNight
39%7%16%22%14%2
1486
August1st to 10thNight
38%8%15%25%13%2
1530
11th to 20thNight
41%9%14%24%11%1
1691
21st to endNight
35%6%12%27%19%1
1980
September1st to 10thNight
42%7%10%23%16%2
1800
11th to 20thNight
35%5%10%21%27%2
1956
21st to endNight
43%6%7%20%21%3
1980
October1st to 10thNight
46%5%10%22%14%4
1980
11th to 20thNight
38%6%12%28%15%1
2194
21st to endNight
47%413%21%14%2
2574
November1st to 10thNight
38%5%11%22%20%4
2407
11th to 20thNight
42%410%23%19%3
2470
21st to endNight
40%414%28%13%2
2470
December1st to 10thNight
46%413%21%14%1
2642
11th to 20thNight
45%413%19%17%2
3288
21st to endNight
50%48%25%12%1
4884

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
31%23%29%15%2
180
11th to 20thDay
37%20%30%9%41
164
21st to endDay
31%23%34%9%31
176
February1st to 10thDay
37%25%24%14%1
339
11th to 20thDay
33%24%33%9%2
416
21st to endDay
34%24%29%9%3
346
March1st to 10thDay
33%21%30%14%2
420
11th to 20thDay
32%21%31%12%3
420
21st to endDay
31%21%30%11%5%2
462
April1st to 10thDay
34%23%25%12%5%1
420
11th to 20thDay
31%19%31%15%4
412
21st to endDay
34%18%31%12%41
420
May1st to 10thDay
35%19%27%12%5%1
423
11th to 20thDay
25%17%37%16%5%1
447
21st to endDay
24%12%31%23%7%3
485
June1st to 10thDay
22%11%33%21%10%2
450
11th to 20thDay
19%16%38%20%7%1
450
21st to endDay
17%14%35%23%8%2
450
July1st to 10thDay
19%9%27%28%14%3
445
11th to 20thDay
15%9%29%30%13%3
444
21st to endDay
15%11%34%29%10%1
488
August1st to 10thDay
14%9%33%28%12%3
446
11th to 20thDay
15%10%28%29%12%5%
439
21st to endDay
12%12%32%22%15%8%
495
September1st to 10thDay
20%9%28%23%14%6%
450
11th to 20thDay
17%13%30%20%11%8%
450
21st to endDay
21%12%36%17%10%5%
450
October1st to 10thDay
31%12%23%21%9%5%
450
11th to 20thDay
22%15%29%22%9%2
421
21st to endDay
29%16%29%18%6%2
396
November1st to 10thDay
21%16%30%21%10%3
365
11th to 20thDay
32%19%26%17%6%
370
21st to endDay
25%18%31%19%6%1
370
December1st to 10thDay
28%25%29%15%4
195
11th to 20thDay
38%22%31%7%2
180
21st to endDay
31%24%28%12%32
198
January1st to 10thNight
24%21%36%16%3
760
11th to 20thNight
31%19%30%18%2
729
21st to endNight
24%21%33%19%3
792
February1st to 10thNight
27%19%32%20%2
720
11th to 20thNight
28%23%34%13%1
703
21st to endNight
31%20%32%15%2
592
March1st to 10thNight
28%19%34%17%2
720
11th to 20thNight
24%22%33%17%3
720
21st to endNight
27%19%34%16%4
792
April1st to 10thNight
27%20%32%19%3
720
11th to 20thNight
23%20%33%21%4
711
21st to endNight
28%17%35%15%5%
574
May1st to 10thNight
29%15%30%21%5%
540
11th to 20thNight
22%17%35%21%5%
488
21st to endNight
21%9%31%30%7%1
389
June1st to 10thNight
20%8%33%31%9%
360
11th to 20thNight
20%10%31%33%6%
360
21st to endNight
17%434%36%8%1
360
July1st to 10thNight
16%5%28%36%15%
350
11th to 20thNight
15%425%41%15%
348
21st to endNight
14%6%30%40%10%
394
August1st to 10thNight
11%5%33%39%11%1
466
11th to 20thNight
14%5%26%39%15%1
627
21st to endNight
16%5%24%34%19%2
792
September1st to 10thNight
17%6%32%32%12%1
720
11th to 20thNight
17%10%26%30%15%3
720
21st to endNight
20%8%31%25%14%2
720
October1st to 10thNight
27%9%28%23%11%3
720
11th to 20thNight
20%13%33%25%9%1
720
21st to endNight
29%14%30%19%7%
792
November1st to 10thNight
19%13%32%25%9%1
740
11th to 20thNight
25%18%32%19%6%1
760
21st to endNight
25%17%31%21%6%
760
December1st to 10thNight
30%16%30%18%5%
760
11th to 20thNight
27%20%31%20%3
760
21st to endNight
28%17%34%17%2
836
Page generated at 2024-01-10 01:25:01. Version ac07

Copyright 2024 Attilla Danko


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